Where is all that water going?

Transcription

1 Where is all that water going? g by Charles Burt Irrigation Training and Research Center California Polytechnic State University San Luis Obispo, CA. USA

2 Some have proposed to conserve 4-6 Million AF/yr in Agriculture with pragmatic, economical measures. All we need to do is find the inefficiencies. Then we ll get rid of them.

3 Fundamental #1 On-farm irrigation savings do not necessarily translate into basin-wide savings.

4 Blanket extrapolation of on-farm efficiency to basin efficiency is: - incorrect - inexcusable

5 We have serious problems We need serious, technically correct solutions.

6 Let s find those inefficiencies!!

7 Irrigation Efficiency isn t the same as fuel efficiency. An inefficient i engine burns up the fuel. Gone. Fini. Adios.

8 Basics There are only a few water destinations in a basin: Change in groundwater storage Surface or subsurface outflows Into the air (ET) Harvested crop (very minor)

9 Possibilities for all the wasted water in the San Joaquin Valley It s hiding in the ground It s running down the San Joaquin River It s sneaking underground to LA There is excessive Evapotranspiration

10 Where is all that wasted water hiding? (Remember, it isn t burned up like gasoline after one use!!!) Possibility #1: That wasted water must be hiding below the ground surface

11 Groundwater levels just east of Stockton

12 MADERA Year = Year = 1970

13 ?? TULARE Year = Year = 1970

14 ?? Bakersfield Year = Year = 1970

15 The first 2 million AF/yr (normal year) we find can t be transferred. We need it to JUST TO BREAK EVEN on groundwater

16 Where did those inefficiencies go? Possibility #2 -Maybe the water is roaring down the San Joaquin River?

17 Wait!! Why do we have the San Joaquin River Restoration program?

18 A trial flow from Friant Dam began on October 1, 2009 It took about 50 days to reach Mendota Dam.

19 A trial flow from Friant Dam began on October 1, 2009 It took about 50 days to reach Mendota Dam. My scientific assessment after analyzing the math for several months: The river was dry.

20 Well, that s 2 out of 3 Water isn t hiding in the ground Water isn t roaring down the San Joaquin River. How about the last one: - Excessive ET?

21 Let s all switch to drip to reduce ET!

22 Let s usedrip to reduce ET ****THERE ARE MANY REASONS THAT FARMERS HAVE CONVERTED TO DRIP**** I am NOT, NOT, NOT saying that Drip Irrigation is bad

23 INCORRECT: Reduce ET via drip/micro. Think about it: Plants have less stress (more Transpiration) The bare ground surface is wet (more Evaporation)

24 How about RDI? (Regulated Deficit Irrigation) This is already STANDARD practice on - Winegrapes (sugar %) - Processing tomatoes (% solids) - Cotton (boll/vegetative balance) - Almonds (hull rot) - Pistachios (just look at the available water supply)

25 RDI Of course, there s always some room for improvement in almost anything. But the facts: 1. There s already extensive under-irrigation. 2. RDI is risky. 3. RDI doesn t account for SALT leaching

26 0 Soil Depth (m) Distance (m) Almonds are damaged ECe color scale (ds/m)

27 Are low on-farm irrigation efficiencies the cause of our water problems? Fact: Not generally in the San Joaquin Valley or Sacramento Valley. The BASIN is the correct scale. Fact: In Imperial Valley, it s different. Exception: Flows to local salt sinks are influenced by low on-farm efficiencies.

28 Confusion between BASIN and ON-FARM efficiencies is: - Common - Erroneous - Harmful Voodoo, Agenda Science

29 The confusion is pervasive The Pacific Institute (2007) quotes Egypt s annual renewable water resource as 86.8 km 3 a surprisingly high figure, given that Egypt s agreed share of the Nile is 55.5 km 3, and rainfall is negligible.

30 We have serious problems. We need technically correct discussions.

31 Of COURSE, we need to continue to improve On-farm irrigation Irrigation district flexibility Groundwater management Fertigation Reduction of embedded energy in water But those actions won t even get rid of the deficit.

32 Demonstration of Differences On-farm vs. Basin Irrigation Efficiencies

33 We are overextended. It s a serious problem. We need technically correct discussions.

34 Those are the facts!! Thank you.